Abstract: A disk drive is disclosed employing a constant contact inertial latch for latching an actuator arm assembly while the disk drive is powered down to protect against physical shocks. The inertial latch comprises a body having a protruding arm and a pivot surface. When the actuator arm assembly is in the latched position, the protruding arm is in constant contact with the actuator arm assembly applying a latching force to the actuator arm assembly.

Abstract: A digital video recorder (DVR) for use with a monitor and a set top box (STB) is disclosed. The STB demodulates program data from a program signal received over a communication channel and generates a STB graphical user interface (GUI). The DVR comprises a local memory for storing the program data received from the STB, a DVR interface for communicating with the STB, and a DVR controller. The DVR controller generates a DVR GUI, and in response to user input, communicates with the STB to coordinate whether the STB GUI or the DVR GUI is displayed on the monitor.

Abstract: A method of writing product servo sectors to a disk of a disk drive is disclosed. An external spiral servo writer writes a plurality of spiral tracks to the disk by actuating in a closed loop system a head positioning pin inserted into the disk drive. Each spiral track comprises a high frequency signal interrupted at a predetermined interval by a sync mark. The high frequency signal and sync marks in the spiral tracks are demodulated to maintain synchronization of a servo write clock as well as maintain the head along a circular target path while writing product servo sectors to the disk.

Abstract: A disk drive is disclosed comprising a disk and a head actuated over the disk. The head comprising a first head terminal and a second head terminal. The disk drive further comprises an electrostatic discharge (ESD) protection circuit comprising a first depletion mode metal oxide semiconductor field effect transistor (MOSFET) and a second depletion mode MOSFET. A first transistor terminal of the depletion mode MOSFETs are coupled to respective head terminals, and a second transistor terminal of the depletion mode MOSFETs are coupled to ground. The gate terminals of the first and second depletion mode MOSFETs are biased to turn on the depletion mode MOSFETs while the disk drive is powered down, thereby grounding the first and second head terminals to protect the head from ESD.

Abstract: A method of estimating a writer/reader gap in a disk drive is disclosed. During a first revolution of the disk, a clock is synchronized to a first preamble and used to measure a write delay to write a second sync mark to the disk relative to a first sync mark. During a second revolution of the disk, the clock is again synchronized to the first preamble and used to measure a read delay required to detect the second sync mark relative to the first sync mark. The writer/reader gap is then estimated in response to the measured write delay and the measured read delay, for example, by computing a difference between the measured write delay and the measured read delay.

Abstract: An isochronous switched fabric network is disclosed comprising a plurality of interconnected switched nodes forming multiple dimensions, each switched node comprising an upstream port and a downstream port for each dimension, each upstream and downstream port comprising an input port and an output port. A discovery facility discovers a depth of each dimension, and discovers resources within each switched node. An addressing facility assigns a matrix address to each switched node, a resource reservation facility reserves resources within each switched node to establish a path through the switched fabric network for transmitting an isochronous data stream, and a scheduling facility schedules isochronous data transmitted through the switched fabric network.

Abstract: A disk drive is disclosed comprising a disk for storing data, the disk comprising a public area for storing plaintext data and a pristine area for storing encrypted data. The disk drive comprises a head for reading the encrypted data from the pristine area of the disk, and a control system for controlling access to the pristine area of the disk. Authentication circuitry within the disk drive is provided for authenticating a request received from an external entity to access the pristine area of the disk and for enabling the control system if the request is authenticated. The disk drive further comprises a secret drive key, and decryption circuitry responsive to the secret drive key, for decrypting the encrypted data stored in the pristine area of the disk.

Abstract: A disk drive is disclosed for optimizing write current settings relative to drive operating characteristics and a plurality of ambient temperature readings. Test data is written to and read from the disk to generate quality metrics that are evaluated to generate an optimized write current setting for each ambient temperature reading. In one embodiment, the optimized write current settings are derived during manufacturing and used in-the-field during normal operation. In another embodiment, the optimized write current settings are re-optimized in-the-field to compensate for changes in the drive operating characteristics that occur over time (e.g., environmental changes and electrical and mechanical changes).

Abstract: A method of manufacturing a disk drive by demodulating product servo sectors and spiral tracks written on a disk of the disk drive is disclosed. An external spiral servo writer writes a plurality of spiral tracks that spiral from an outer diameter to an inner diameter of the disk. Each spiral track comprises a high frequency signal interrupted at a predetermined interval by a sync mark. The spiral tracks are used to write product servo sectors to the disk during a fill operation. Common circuitry, such as burst demodulation circuitry, is used to demodulate the high frequency signal in the spiral tracks during the fill operation as well as demodulate the product servo sectors.

Abstract: A disk drive is disclosed comprising a disk, a head, and a voice coil motor (VCM) for actuating the head over the disk. The disk drive executes a rotational position optimization (RPO) algorithm to select a next command to execute relative to an estimated seek time computed for each command in a command queue. A motor capability of the VCM is estimated and used to modify the estimated seek time for each command in the command queue to thereby optimize the RPO algorithm.

Abstract: A method and apparatus is disclosed for adjusting the track density over the disk radius by changing the slope of spiral tracks used to servo write a disk drive. A plurality of spiral tracks are written to the disk wherein each spiral track comprises a high frequency signal interrupted at a predetermined interval by a sync mark. A slope of the spiral tracks over a first radial segment of the disk is substantially steeper than the slope of the spiral tracks over a second radial segment of the disk. The head internal to the disk drive is used to read the spiral tracks in order to write product servo sectors to the disk to define a plurality of data tracks. The steeper slope of the spiral tracks over the first radial segment causes a track density of the data tracks to be lower over the first radial segment compared to the track density of the data tracks over the second radial segment.

Abstract: A disk drive is disclosed comprising a disk having an asynchronous partition and a first and second isochronous partition, wherein the asynchronous partition is located between the first and second isochronous partitions in order to reduce the seek time for the disk drive when seeking between the asynchronous and isochronous partitions.

Abstract: A disk drive is disclosed comprising a disk and a head actuated radially over the disk. An external servo writer is used to write reference servo bursts to the disk at a coarser radial resolution than product servo bursts. During a self servo writing operation, the reference servo bursts are processed to servo circularly to write a first set of product servo bursts to the disk. The reference servo bursts are also processed to servo spirally to write a second set of product servo bursts to the disk.

Abstract: An integrated circuit is disclosed for selectively encrypting plaintext data received from a first device to produce encrypted data to send to a second device. The integrated circuit comprises controllable encryption circuitry comprising a data input, an enable input, and a data output. The integrated circuit further comprises a plaintext input for providing the plaintext data to the data input, an encrypted text output for providing the encrypted data from the data output, and a first control input for receiving a first device authentication signal for authenticating the first device. The integrated circuit further comprises a verification circuit responsive to the first device authentication signal for producing a first verification signal for use in controlling the enable input of the encryption circuitry to enable the encryption circuitry to provide the encrypted data via the encrypted text output.

Abstract: A disk drive is disclosed comprising a spindle motor comprising a plurality of windings for rotating a disk. The spindle motor is rotated by commutating the windings over a plurality of commutation states, wherein audible noise generated by the disk drive is reduced by phase modulating the commutation interval. Further audible noise reduction is achieved by modulating a current applied to the windings which substantially reduces discontinuities in the torque output of the spindle motor caused by phase modulation of the commutation intervals.

Abstract: A disk drive is disclosed wherein a BEMF speed error is measured during a BEMF spindle speed control mode, and a spindle control current is updated in response to the BEMF speed error to drive the disk at an operating speed. A reference time period (RTP) is calibrated, and a sinusoidal error in a wedge time period (WTP) due to eccentricity in the disk rotating is estimated to generate an eccentricity compensation value. After switching to a wedge spindle speed control mode, an actual WTP is detected and a wedge speed error is generated in response to the RTP, the detected actual WTP, and the eccentricity compensation value. The disk is then maintained at the operating speed by updating the spindle control current in response to the wedge speed error.

Abstract: A disk drive is disclosed employing a primary actuator for rotating an actuator arm about a pivot in coarse movements, and first and second secondary actuators coupled to the actuator arm for actuating first and second heads in fine movements. A servo control system generates a first control signal applied to the first secondary actuator to position the first head over the first disk surface in fine movements while accessing the first disk surface. The servo control system phase shifts the first control signal by a predetermined phase to generate a second control signal applied to the second secondary actuator to attenuate excitation of at least one arm vibration mode.

Abstract: A disk drive is disclosed comprising a head, a disk and a spindle motor for rotating the disk. An internal supply voltage is generated from a back EMF (BEMF) voltage across the windings of the spindle motor. The internal supply voltage is applied to a voice coil motor for use in parking the head during a spin-down mode. The internal supply voltage is compared to a threshold in order to activate a demand limit control signal. A periodic signal periodically disconnects the internal supply voltage from the VCM while the demand limit control signal is active.

Abstract: A disk drive is disclosed comprising a spindle motor for rotating a disk, wherein the current applied to the spindle motor is controlled by adjusting a duty cycle of a pulse width modulated (PWM) signal. A current sensor generates a current sense signal representing a current flowing from a supply voltage. The current sense signal is integrated to generate an integration signal. The integration signal is compared to a threshold, and the result of the comparison is used to adjust the duty cycle of the PWM signal. In this manner the disk drive draws essentially constant average input current from the supply voltage which decreases the spin up time of the disk.

Abstract: A disk drive is disclosed which executes a rotational position optimization (RPO) algorithm to select a next command to execute from a command queue relative to an estimated access time. If an external vibration is detected, the RPO algorithm increases at least one of an estimated seek latency, an estimated settle latency, and an estimated rotational latency for each command in the command queue.